Mercury, the smallest planet in our solar system, may be hiding an important secret: a diamond layer up to 18 km thick beneath its crust.
This theory comes from scientists in China and Belgium, who analyzed data from NASA’s MESSENGER spacecraft, collected between 2004 and 2015, to study Mercury’s internal structure.
The researchers to suggest two processes that could have led to the formation of this diamond layer. First, the crystallization of Mercury’s ancient magma ocean may have created a very thin diamond layer at the core-mantle interface.
More importantly, they believe that the crystallization of Mercury’s metallic core played a crucial role.
Olivier Namur, member of the research team and associate professor at KU Leuven, explained that when Mercury formed about 4.5 billion years ago, its metal core was completely liquid and gradually crystallized over time.
Under the extreme pressure of Mercury’s interior, the carbon in the mantle could have turned into diamond, which then floated to the top of the core, forming a separate layer between the core and the mantle.
To test their theory, scientists used a large-volume press to simulate the high pressures and temperatures of Mercury’s interior. They subjected synthetic magnesium silicate to a pressure of seven gigapascals and heated it to 2,177°C (3,950°F).
These experiments showed how minerals would have transformed during Mercury’s formation, supporting the possibility of diamond formation under such conditions.
Namen noted that these findings could indicate differences in how Mercury formed compared to other planets, such as Earth and Mars.
Previous theories have suggested that the Earth’s mantle may contain more than a trillion tons of diamonds, buried more than 100 miles (160 km) below the surface, much deeper than any human drilling has reached.
This new research, published June 14, adds to our understanding of Mercury and highlights the potential for important discoveries about the formation and composition of planets in our Solar System.
